Process for the preparation of crystalline poly(ethylene terephthalate)

Abstract

A process for preparing a crystalline poly(ethylene terephthalate) having an inherent viscosity of at least 0.5 comprising (A) preparing an admixture of molten poly(ethylene terephthalate) and a zeolite, and (B) cooling the admixture at a rate less than about 300 degrees C. per minute to a temperature less than about 80 degrees C.

We claim: 
     
       1. A process for preparing a crystalline poly(ethylene terephthalate) having an inherent viscosity of at least 0.5 comprising (A) preparing an admixture of molten poly(ethylene terephthalate) and a zeolite, and   (B) cooling the admixture at a rate less than about 300 degrees C per minute to a temperature less than about 80 degrees C.   
     
     
       2. The process of claim 1 wherein the amount of zeolite is greater than 0.1 weight percent. 
     
     
       3. The process of claim 1 wherein the zeolite has a particle size in the range of 0.1 to 50 microns. 
     
     
       4. The process of claim 1 wherein the zeolite is selected from the group consisting of 3A, 4A, 5A, NaY, 13X, and mordenite. 
     
     
       5. The process of claim 4 wherein the zeolite is selected from the group consisting of NaY, mordenite and 4A. 
     
     
       6. A process for preparing a crystalline poly(ethylene terephthalate) having an inherent viscosity of at least 0.6 comprising (A) preparing an admixture of 75 to 99.9 weight percent molten poly(ethylene terephthalate) and 25 to 0.1 weight percent of a 4A zeolite powder having a particle size in the range of 0.1 to 5 microns, and   (B) cooling the admixture at a rate of less than 300 degrees C per minute to a temperature less than 80 degrees C.